Re: Single element arrays as function parameters

[Adam Beneschan <adam@irvine.com>]

On Jun 10, 2:28 pm, Mart van de Wege <mvdw...@mail.com> wrote:
> "J-P. Rosen" <ro...@adalog.fr> writes:
> > Le 10/06/2011 22:11, Mart van de Wege a écrit :
>
> >> M := Init.Creature( Name => "Dwarf",
> >>                       Creature_Type => Humanoid,
> >>                       Creature_Subtype => (Dwarf) );
>
> >> The above call fails to compile:
>
> >> test_create.adb:13:45: positional aggregate cannot have one component
> > This is the clue: it is interpreted as a parenthesized value, not as an
> > aggregate. Just write:
>
> >  M := Init.Creature( Name => "Dwarf",
> >                           Creature_Type => Humanoid,
> >                           Creature_Subtype => (1 => Dwarf) );
>
> Brrr. That works, but it looks a bit...ugly. Especially considering that
> creatures only having one subtype[1] is the norm in Dungeons&Dragons
> (the application in question is meant to help manage large amounts of
> data to assist in running a campaign).
>
> If there is no more elegant solution, I'll fix this by adding the
> necessary remarks to the API description, in the unlikely case that
> someone else except me is ever interested in this application.

Your original post doesn't make sense; it defines a function Creature
with parameters Name, Race, Level, and Player, but then you're calling
a function Creature that has parameters Name, Creature_Type, and
Creature_Subtype.  Actually, though, this would explain some of the
error messages in your original post (such as missing "Race" and
"Level" arguments).

Assuming you meant something like

  Race => (Dwarf)

one solution is to define an overloaded Creature function that takes a
single element instead of an array.  Assuming MM_Subtype is an array
of Element_Type (since I don't know what the actual name is), you can
write something like

    function Creature (Name     : in String;
                       Race     : in Element_Type;
                       Level    : in Positive;
                       Player   : in String)
                      return Character_Ptr is
    begin
       return Creature (Name => Name, Race => (1 => Race), Level =>
Level, Player => Player);
    end Creature;

and now the rest of your program can call Creature with either a
single element or an array as the Race.  (And you wouldn't need to
parenthesize the single element when you call it, but you could.)

                             -- Adam